Revert of Revert of Split out CSSParser public API

Source/core/css/CSSStyleSheet.cpp

Index: Source/core/css/CSSStyleSheet.cpp
diff --git a/Source/core/css/CSSStyleSheet.cpp b/Source/core/css/CSSStyleSheet.cpp
index 0e80beff707d561c2bc6c78d114dc075323ef203..fa9b7746e35b5be26ed8a6d80b1616a561e76065 100644
--- a/Source/core/css/CSSStyleSheet.cpp
+++ b/Source/core/css/CSSStyleSheet.cpp
@@ -28,11 +28,11 @@
 #include "core/SVGNames.h"
 #include "core/css/CSSCharsetRule.h"
 #include "core/css/CSSImportRule.h"
-#include "core/css/parser/BisonCSSParser.h"
 #include "core/css/CSSRuleList.h"
 #include "core/css/MediaList.h"
 #include "core/css/StyleRule.h"
 #include "core/css/StyleSheetContents.h"
+#include "core/css/parser/CSSParser.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/dom/Node.h"
@@ -310,8 +310,7 @@
         return 0;
     }
     CSSParserContext context(m_contents->parserContext(), UseCounter::getFrom(this));
-    BisonCSSParser p(context);
-    RefPtrWillBeRawPtr<StyleRuleBase> rule = p.parseRule(m_contents.get(), ruleString);
+    RefPtrWillBeRawPtr<StyleRuleBase> rule = CSSParser::parseRule(context, m_contents.get(), ruleString);
 
     if (!rule) {
         exceptionState.throwDOMException(SyntaxError, "Failed to parse the rule '" + ruleString + "'.");